EPIC模型对华北平原冬小麦与夏玉米生长和产量模拟的适用性评价

为验证EPIC模型应用于华北地区农业生产的适用性,利用禹城生态试验站的试验观测数据对该模型参数进行了修订,构建了适合华北平原的模型参数数据库,并分别验证了2003-2005年冬小麦、2004年夏玉米的叶面积指数、生物量和产量模拟的精度与适用性。结果表明,EPIC模型对禹城站冬小麦和夏玉米叶面积指数和地上部生物量的模拟值和实测值随时间的变化趋势大体一致,决定系数均高于0.81;EPIC模型对禹城站2004、2005年冬小麦产量的模拟误差分别为1.61%和-2.56%,对2004夏玉米产量的模拟误差为-2.60%。因此,该模型模拟产量的绝对误差低于2.60%,适用于华北平原冬小麦和夏玉米的产量评估。     

基于Sentinel-2多光谱数据和机器学习算法的冬小麦LAI遥感估算

为了丰富大田尺度下冬小麦叶面积指数的遥感估算方法并提高估算精度,以关中地区冬小麦为对象,基于Sentinel-2多光谱卫星数据与地面同步观测的冬小麦叶面积指数样点数据,应用偏最小二乘回归(PLSR)、反向传播神经网络(BPNN)和随机森林(RF)法构建冬小麦叶面积指数估算模型,进行区域冬小麦叶面积指数遥感反演。结果表明,Sentinel-2多光谱卫星影像中心842nm近红外B8波段与冬小麦叶面积指数相关性最好,样本总体相关系数为0.778;植被指数中反向差值植被指数(IDVI)与冬小麦叶面积指数相关性最好,样本总体相关系数为0.776。各种估算模型中LAI-RF模型预测效果最佳,r~2为0.72,RMSE为0.53,RE为16.83%。基于LAI-RF估算模型,应用Sentinel-2多光谱卫星数据较好地反演了研究区冬小麦叶面积指数区域分布,其结果总体上与地面真实情况接近,说明以Sentinel-2卫星影像数据建立LAI-RF估算模型,可应用于区域冬小麦LAI反演制图。     

基于遥感信息和WOFOST模型参数同化的冬小麦单产估算方法研究

为探讨遥感信息和作物生长模型在作物估产方面的优势互补特性,选取河北省藁城市冬小麦作为研究对象,采集多个关键生育时期的生理生化、农田环境、气象等数据,并获取准同步的环境减灾小卫星HJ-CCD影像数据,采用植被指数反演冬小麦叶面积指数（LAI）,基于扩展傅里叶振幅灵敏度检验法(EFAST)对WOFOST作物模型的26个初始参数进行全局敏感性分析,筛选敏感性参数,调整WOFOST模型的核心参数,利用查找表优化算法构建基于WOFOST模型和遥感LAI数据同化的区域尺度冬小麦单产预测模型,并定量预测区域冬小麦单产水平。结果表明,增强型植被指数（EVI）是遥感反演LAI的最佳植被指数(开花期建模r=0.913,RMSE=0.410,灌浆期建模r=0.798,RMSE=0.470),预测能力最强(开花期r=0.858,RMSE=0.531,灌浆期r=0.861,RMSE=0.428);筛选出6个待优化参数,即TSUM1、SLATB1、SLATB2、SPAN、EFFTB3和TMPF4;产量预测精度r=0.914,RMSE=253.67 kg·hm_-2,找到了待优化参数的最佳取值,最终完成了单产模拟。     

冬小麦花期生理形态指标与卫星遥感光谱特征的相关性分析

为提高冬小麦花期长势遥感监测的精确性与普适性,在集丘陵地、河滩地及平原地为一体的冬小麦种植区域设计了田间试验,利用卫星影像信息结合地面GPS定点试验数据,在分析利用遥感技术监测冬小麦花期LAI和生物量两个主要群体长势指标可行的基础上,对卫星遥感光谱信息与冬小麦花期的主要生理生化指标(叶片叶绿素含量、叶片类胡萝卜素含量、叶片水分含量和叶片氮素含量)进行了综合分析.结果表明,NDVI(归一化植被指数)与LAI、叶片氮素含量和叶片水分含量的相关性较好,RVI(比值植被指数)与生物量和叶片类胡萝卜素含量的相关性较好,GVI(绿度植被指数)与叶片叶绿素含量的相关性较好,且均达到显著水平.说明NDVI、RVI及GVI是较为理想的可用于监测冬小麦花期生理形态指标的敏感遥感指数.进一步以这些敏感遥感指数作为因变量建立了冬小麦花期生理形态指标的遥感监测模型.利用本模型可以反演多个生理形态指标,便于对冬小麦花期的长势情况进行综合分析与判断.     

水稻叶龄与叶面积指数动态的模拟研究

 依据不同类型品种的播期试验和氮肥试验结果,建立了水稻叶龄与叶面积指数(LAI)的模拟模型。叶龄模型采用幂函数描述叶片出生与播后累积热时间(TTS)的关系,TTS的计算定量了温度与出叶速率之间的非线性关系。叶面积指数模拟包括两个阶段:在指数生长阶段,LAI随播后累积生长度日(GDD)呈指数式增长,同时受到氮素营养水平调节;当LAI≥1.6时进入非指数生长阶段,采用比叶面积法模拟,LAI是比叶面积与绿叶干物质量的乘积。绿叶干物质量是绿叶分配指数与地上部干物质量的乘积,比叶面积(SLA)为GDD的函数,同时考虑植株氮素营养因子对SLA的影响。利用生态条件和栽培条件差异较大的试验资料对模型进行了验证。结果表明,模型能较好地模拟不同条件下叶片的出生动态和LAI变化动态,表现出较强的适用性,具有参数少、易确定、简便实用的特点。     

冬小麦冠层降水截留性能研究

为定量分析冬小麦冠层降水截留量,采用"简易吸水法"分别研究了冬小麦单茎和群体的冠层截留性能,并对其影响因素进行了探讨。结果表明,在冬小麦抽穗前,叶数对单茎截留量影响显著(P<0.05),而对截留率影响不明显。在叶数相同条件下,单茎截留量在不同生育期间差异显著(P<0.01)。冬小麦单茎截留量随叶面积的增大而增大,而叶面积对截留率影响不显著。冬小麦单茎截留量与株高、鲜重呈线性正相关,相应截留率则与株高、鲜重呈线性负相关;群体截留量与叶面积指数(LAI)、地上部生物量呈线性正相关,相应截留率则与LAI、地上部生物量呈线性负相关。从拔节至成熟,冬小麦冠层截留量先增加后减少,最大冠层截留量出现在抽穗期(1.28mm),且不同生育期截留量差异极显著(P<0.01);相应截留率在不同生育期的变化无规律,各生育期间差异不显著。     

基于HJ-1A/1B影像的冬小麦开花期主要生长指标遥感定量监测研究

为建立冬小麦开花期生长状况的遥感监测方法和技术,结合2011-2013年定点观测试验,以环境减灾卫星HJ-1A/1B数据为遥感影像源,着重分析了样本试验区冬小麦开花期主要生长指标间及其与籽粒品质、产量和卫星遥感变量间的定量关系,分别构建及评价基于HJ-1A/1B影像遥感变量的开花期叶面积指数、生物量、SPAD值和叶片含氮量监测模型。结果表明,在冬小麦开花期,作物氮反应指数(NRI)、绿色归一化植被指数(GNDVI)可分别作为监测冬小麦叶面积指数和生物量的敏感遥感变量,结构加强色素植被指数(SIPI)和SIPI可作为监测冬小麦SPAD值和叶片含氮量的敏感遥感变量,所构建的遥感监测模型可靠,模型的决定系数(r2)分别为0.73、0.69、0.62和0.61,均方根误差(RMSE)分别为0.79、1 068kg·hm-2、4.66和0.42%。利用遥感数据绘制的冬小麦开花期主要生长指标遥感监测等级分布空间量化表达图与实际相符。     

夏玉米长势卫星遥感动态监测指标研究

通过野外样点布设获取地面农学参数平均株高、群体密度、干物重和叶面积指数,经过频数统计分析,获得夏玉米一、二、三类苗苗情农学指标。结合MODIS遥感数据,进行农学参数和归一化植被指数(NDVI)的相关分析,结果显示,NDVI和平均株高、叶面积指数以及生物量都呈显著正相关,其中NDVI和叶面积指数关系最为显著(各生育期R2>0.623),因此可通过建立叶面积指数和NDVI的关系确定夏玉米长势遥感指标,为大面积遥感监测夏玉米长势提供科学依据。     

图像处理技术在冬小麦叶面积指数测定中的应用

为了探讨利用图像处理技术测定冬小麦叶面积指数的可行性,在室外光照条件下．固定数码相机高度垂直拍摄冬小麦群体图像,利用图像处理技术获取小麦冠层的图像叶面积指数(ILAI),并用手工测量获得小麦群体实际叶面积指数(LAI),建立ILAI和LAI间与施肥处理有关的关系模型,对该模型的稳定性和实用性进行统计检验。试验结果表明,利用图像处理技术通过ILAI获取小麦LAI是可行的,且简便易行,测量精度和效率都很高。     

基于适宜尺度选择的冬小麦赤霉病遥感监测

为快速、准确获取江淮麦区县域冬小麦赤霉病发生信息,选用中、高空间分辨率卫星遥感影像做多尺度信息融合研究。在筛选适宜冬小麦田块分布特征的空间尺度遥感影像基础上,通过分析冬小麦长势指标和赤霉病病情指数之间的互作关系,构建基于多农学参数的冬小麦赤霉病估测模型,并对县域冬小麦赤霉病空间变化进行遥感监测。结果表明:(1)2m×2m、8m×8m和16m×16m三种空间尺度融合影像的均值相差不大,平均梯度和标准差存在明显差异。16m×16m融合影像的清晰度最好,信息量也多,比较适合研究区域冬小麦田块分布特征。(2)16m×16m融合影像提取的归一化植被指数(NDVI)和比值植被指数(RVI)值明显高于2m×2m和8m×8m融合影像,说明16m×16m融合影像光谱信息量较丰富,有利于冬小麦的识别。(3)冬小麦叶面积指数、叶片叶绿素含量和地上部生物量是影响赤霉病发生的主要长势指标。基于主要长势指标构建冬小麦赤霉病估测模型,平方根误差(REMS)为10.5%,相对误差为14.6%。该方法可以实现对县域冬小麦赤霉病空间变化的有效监测。     

Studies on natural repellents against potato tuber moth (Phthorimaea operculella Zeller) in country stores

Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong (1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage, sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over 45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield of a subsequent crop.     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

Summary

The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices.     

In vitro antimicrobial activity of different accessions ofSolanum commersonii Dun. from Uruguay

Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds.     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

Extreme resistance to infection by potato virus X in genotypes of wild tuber-bearingSolanum species

Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta. Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X¹ (also called RX_act).     

Marine Pharmacology in 2009–2011: Marine Compounds with Antibacterial,Antidiabetic, Antifungal,Anti-Inflammatory,Antiprotozoal, Antituberculosis,and Antiviral Activities; Affecting the Immune and Nervous Systems,and other Miscellaneous Mechanisms of Action ?

The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998–2008 reviews of this series. The pharmacology of structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009–2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories.     

Recent Modifications of Chitosan for Adsorption Applications: A Critical and Systematic Review

Chitosan is considered to be one of the most promising and applicable materials in adsorption applications. The existence of amino and hydroxyl groups in its molecules contributes to many possible adsorption interactions between chitosan and pollutants (dyes, metals, ions, phenols, pharmaceuticals/drugs, pesticides, herbicides, etc.). These functional groups can help in establishing positions for modification. Based on the learning from previously published works in literature, researchers have achieved a modification of chitosan with a number of different functional groups. This work summarizes the published works of the last three years (2012–2014) regarding the modification reactions of chitosans (grafting, cross-linking, etc.) and their application to adsorption of different environmental pollutants (in liquid-phase).     

Pharmacokinetics of Marine-Derived Drugs

Marine organisms represent an excellent source of innovative compounds that have the potential for the development of new drugs. The pharmacokinetics of marine drugs has attracted increasing interest in recent decades due to its effective and potential contribution to the selection of rational dosage recommendations and the optimal use of the therapeutic arsenal. In general, pharmacokinetics studies how drugs change after administration via the processes of absorption, distribution, metabolism, and excretion (ADME). This review provides a summary of the pharmacokinetics studies of marine-derived active compounds, with a particular focus on their ADME. The pharmacokinetics of compounds derived from algae, crustaceans, sea cucumber, fungus, sea urchins, sponges, mollusks, tunicate, and bryozoan is discussed, and the pharmacokinetics data in human experiments are analyzed. In-depth characterization using pharmacokinetics is useful for obtaining information for understanding the molecular basis of pharmacological activity, for correct doses and treatment schemes selection, and for more effective drug application. Thus, an increase in pharmacokinetic research on marine-derived compounds is expected in the near future.